Controller for fluid pressure operated devices



Feb. 20, 1962 L. CHARLSON 25,126

CONTROLLER FOR FLUID PRESSURE OPERATED DEVICES Original Filed Nov. 25, 1958 4 Sheets-Sheet 1 INVEN TOR.

Lr/wv L. CMRLSON BY A TTORNEYS Feb. 20, 1962 1.. CHARLSON 25,126

CONTROLLER FOR FLUID PRESSURE OPERATED DEVICES Original Filed Nov. 25, 1958 4 Sheets-Sheet 2 R; $5 W \m' R. M I l I l m s L [low 191 I I0. I m M m G H m 00 NH I a H U$1 NIH L 2 M b E a MN MN \W/ L L \w o a, um i \z/z k E m a ow :Iv 3 2 3 w q w .M V m .1

A T TORNEYQ Feb. 20, 1962 L. L. CHARLSON Re. 25,126

I CONTROLLER FOR FLUID PRESSURE OPERATED DEVICES Original Filed Nov. 25, 1958 4 Sheets-Sheet 3 a 7' l Eb Ill 8 INVENTOR. LYNN L. CHARLSON A T TORNEXS Feb. 20, 1962 L. L. CHARLSON 25,126

CONTROLLER FOR FLUID PRESSURE OPERATED DEVICES Original Filed Nov. 25, 1958 4 Sheets-Sheet 4 Fi e. 11 Fza. J2

62 65 N m I v 32. 54 I 2 6+ 2 IN VEN TOR.

LYNN L. CHARLsON BY Av-ToarvgYs United States Patent 01 25 126 I CONTROLLER FOR FLUlD PRESSUREJOPERATED,

M t r enclo d in hea y b s ['Ilapp ars in t e originalpatent but forms no part of this reissue specification; matter printed in italics indicates the additions made 'by reissue.

My invention relates generally t control apparatus for fluid pressure operated devices and more particularly to fluid valve structures for controlling: actuation of devices which operated by fluid under pressure,

An important object of my invention is the provision of a novel valve structure including a movable valve element whereby the amount ofmovement of a movable fluid pressure operated member in a given direction is dependent on the amount of movement of said movable valve element in a given direction.

Another object of my invention is the provision of a control valve having novel follow-up mechanism which is responsive only to flow of a given quantity of fluid through said control valve to close the valve, thus eliminating the necessity for mechanical linkage between the valve and the fluidpressur-e operated device controlled thereby. To this end I provide a valve having a primary valve element under control of an operator, a movable follow-up valve element, and a servornotor connected to the follow-up, element, the valve structure having passage means whereby all of the fluid under pressure flowing between a source and said fluid-pressure operated device, through said valve, is conducted through said servomotor .to operate the same to move the follow-up element in a direction to stop the fluid flow to said device.

Another important object of my invention is the provision of a novel control apparatus as set forth, having novel means whereby the servomotor can be operated by the operator, in the absence of failure of said source 10 provide. fluid .under pressure, so that the servomotor operates as a pump to deliver the desired quantity of fluid under pressure to said fluid-pressure operated device.

Still another object of my invention is the provision of control apparatus of the above type which can be easily installed in fluid pressure systems involving dilferent types of fluid-pressure operated devices. to control operation thereof in opposite directions, and being located at remote points from said devices, if desired.

The above, and still further highly important objects nd van ages o my nv tion i l become pp n fr m he lowing detail p cificat ons appende c a m ndattaq d awin sieterring u he rawing wh illust a e he in nt n n which lik efere chara te i d at li e parts t oughou th ev ral view B G. 1 is a d g am showing my n l con rol er a used in the power steering system of a vehicle.

FIG- 2 is. an enl ged v ew partly n e eva n a pa t y i ax a sec ion ta en subst ntially n. h line 2-4 of IG- 1, some pa t being bru en way;

3 n ax al se t on taken substant l y 9n th line 3-3 of FIG. 2.;

IG- 4 is a t ansver e sect on ta en substa t a l 0. 1 th n 4- o L G- ome p rts b ing broken away;

5 is a fragm ntary view n s de e evat on o one of the valve elements of my invention;

FI 6 is a v e in idetelevation of the fo low-up valve element of my invention; and

p Re. 25,126 Re'issued Feb. 20, 1962 ice FIGS, 7-14 are views in transverse section taken rep c v ly on th nes 0-.10,. .1. 1=2.12, 13713, and 14. 14 of FIG. -3.

In the preferred embodiment of the invention illustrated, my novel controller is indicated in its entirety by the numeral 1, and, for the purpose of thfi Present xamp e, i ust at d in. G- 1 as use in h po steering mechanism for a vehicle. The. controller 1 i o e a es ue r dy ruct e 2 avin a inlet 3 w w u is. wunwte wndu 4 ough h ch flu d der pressure is introduced to the controller 1 from a suitable r su h- 5 Pump 5 t a i co cte n a r es uir or tenkfi hyndu t T e c i g s fur he p vided with anvoutlet 8 f0r return of fluid to the tank or reservoir 6 through a conduit 9 suita'bly connected to he ou l t 8- h a n 2-v s u h r p v de with a pair of ports 10 and 11 to which respective conduits 12 and 13 are connected, these conduits leading to opposite finds. of a fluid pressurecylinder 14 having mounted for axial reciprocat ory movement therein a piston-equipped plunger rod 15. Said plunger rod 15 is connected to the s e i g l nka e. 1:6 o h e ic e n S by m ans of the usual bell crank17 and rigid link 18. The steering linkage 16-,is connected to the steerable wheels 19 in the usual manner.

The casing or body structure 2 comprises a tubular casing section 20 which defines the inlet and outlet 3 and :8 respectively and theports 10 and 11, a mounting flange 21 that-is rigidly secured .to one end of the tubular section 20 by machine screws or the like 22 see FIG. 14, a b a ngp t 2 an i t lly o h d mem e 2 nd an end cap;25. With further reference to FIG. 14, it will be seen that the mounting flange 21 is provided with circurnferentially spaced apertures 26 for the reception of mounting bolts or the like 27, by means of which the controller 1 may be mounted on a suitable wall or mounting bracket 28 of the vehicle, as shown, see FIG. 1. With reference toF IG. 3 it will be seen that the bearing plate 23, internally toothed member 24, and end cap 25 are rigidly secured in end to end relationship to the .opposite en o t e tubu ar h u ng s t 20 by me s of chine screws 29.

, The tubular housing or casing section '20 has an in- .ternal cylindrical Wall 30 which, together with the mounting flange 21 and annular bearing plate 23 defines a cylindrical chamber for the reception of concentric primary and. follow-up valve elements 31 and 32 respectively.v The followaup valve element 32 is in the .113- wtru efof a tubular sleevewhich closely engages the inner ovlindrical wall 30, for rotary movement :with respect to, the casing section 20 and concentric therewith, the opposite ends .of the follow-up --valve element 32 having substantiallyrabutting engagement with an inner surface portion otthe mounting flange 21 and with the bearing plate 23. The primary valve element 3.1 is cylindric' n o m an h llow for the greater part or its lengthh re y t defin an xi l r s or pa sa e 33 which. extends inwardly from the ,endthereof adjacent the bear nen ate the a v e emen 1 being uas ugly r c ve within. e in ow-up va v e ment 32 an concentric therewi h. the end pf the primary, valve eleme t .31 is. in sub t nti lly abutt ng e a n ip with wthe.hearing plate 23, the QPPQSite end of the valve .elemerit 3.1 h v ng abutt ng enga eme t a h s b in; 4 ed in he mountin ng {Hi -in er and 9f th axial ecc sl s ined y the inn r n r spnt a shafi 3. w ichertend axi l y Qutwardl) om the adiacent end Qf th prima va velem 3. nd which is journalled in the mounting flange 21, the outer endpqrt cu .ut t ec nt rshat .he n isn n or Otherwise a ra gedas ind at dat 3. tor rece tion thcreon of a suitable control element such as a steering wheel on the screw threaded end 39 of the shaft 35. With reference to FIGS. 2 and 3, it will be seen that an O-ring 40 is contained in a suitable annular groove in the mounting flange 21 and encircles the shaft 35 adjacent the thrust bearing 34 to prevent leakage of fluid from within the housing or body structure 2 adjacent the shaft 35. A second O-ring 41 is mounted in the mountingflange 21 and provides a-seal between the mounting flange 21 and the tubular body section 20.

The primary valve element 31 is coupled to the followup valve element 32 for limited rotary movement in opposite directions with respect to the follow-up valve element 32, and for common rotary movement with the follow-up valve element 32. Means for thus coupling the valve elements together comprises a transverse drive pin 42 which extends radially through a pair of diametrically opposed circumferentially extended slots 43 in the primaryvalve element 31, see particularly FIG. 4, the opposite-ends of the drive pin 42 being snugly received in diametrically opposed apertures 44 in the follow-up valve element 32. When the primary valve element 31 is rotated in either direction from its neutral position shown in FIG. 4, the drive pin 42 becomes engaged by the opposite ends of the opposed slots 43, after which the continued rotary movement of the primary valve element 31 will cause similar rotary movement to be imparted to the follow-up valve element 32. For the purpose of yieldingly urging the valve elements 31 and 32 toward a neutral relationship wherein the drive pin 42 is centered in the slots 43, I provide a plurality of resilient leaf springs 45 which extend radially through aligned diametrically opposed notches 46 and 47 in the primary and follow-up valve elements 31 and 32 respectively, and through a groove or channel 48 in the inner end of the control shaft 35 and aligned with the notches 46 and 47. Preferably, the primary valve element 31 and control shaft 35 are fabricated separately, the inner grooved end of the shaft 35 being welded or otherwise rigidly secured within the adjacent end portion of the tubular section of the valve element 31.

The primary valve element 31 is formed to provide, in axially inwardly spaced relation to its opposite ends, a pair of radially outwardly opening circumferential channels 49 and 50, one side of the former defining axially inwardly extending radially outwardly opening recesses 51 in circumferentially spaced relationship. The chanspaced radially outwardly opening circumferential channels-57, 58, 59'and 60, see particularly'FlG. 6. The several channels 57-60 are disposed in registration with respective ones of the openings'in the tubular casing 20, the channel 57 being in registration with the inlet 3, the channel 58 with the delivery port 10, the channel 59 with the delivery port 11, and the channel 60 with the outlet 8. A pair of axially spaced circumferentially extended rows of apertures or passages 61 extend radially inwardly of the channel 57 to the interior of the follow-up valve element 32, each of the apertures 61 being in register with a dilferent one of the apertures 53 in the primary valve element 31 when the primary valve element 31 is in its neutral position relative to the follow-up valve element 32, wherein the drive pin 42 is centered in the slots 43. Also extending radially inwardly from the bottom of the channel 57 is a plurality of circumferentially spaced openings 1 or passages 62 that are in constant communication with the channel 49 of the primary valve element 31, whereby fluid under pressure is supplied by the pump 5 to the channel 49-and recesses 51 at all times and irrespective of the relative positions of the valve elements 31 and 32. A plurality'of circumferentially spaced radial passages 63 extend inwardly from the outer surface of the follow-up valve element 32 intermediate the channels 57 and 58 thereof, there being a like number of radial passages 63 as that of recesses 51 and axial grooves 54 combined. As

, shown best in FIG. 10, the row of radial passages 63 overlies the recesses 51 and adjacent end portions of the grooves 54.

The follow-up valve element 32 is formed to provide a plurality of slot-like passages 64 which extend radially inwardly from the channel 58 and which are disposed to register selectively with the openings 55 and grooves 54 of the primary valve element 31 upon relative rotation between the valve elements 31 and 32. The slot-like passages 64 are equal in number to one-half of the radial passages 63, the passages 64 being aligned with alternate ones of the radial passages 63 axially of the valve element nel communicates with the recess or passage 33 by of circumferentially spaced radially outwardly opening I passages in the nature of grooves 54 which extend axially of the primary valve element 31, the grooves 54 terminate at one end between adjacent recesses 51 and'in circumferentially spaced relation thereto, and at their other end terminating in axially spaced relation to the channel 50. Intermediate the grooves 54, the valve element 31 is provided with pairs of radial openings 55 and 56 which com municate with the passage or recess 33, the radial open ings 55 being located in closely spaced relation to adjacent recesses 51, and the openings 56 being disposed adjacent the opposite ends of the grooves 54, see particularly FIG. 5. It will be noted that axially aligned pairs of the openings 55 and 56 are also disposed in axial alignment with a different one of the recesses 51, for a purpose which will hereinafter become apparent. I

The outer cylindrical surface of the follow-up valve element 32 is formed to provide a plurality of axially 32, as best shown in FIG. 6. Similar slot-like passages 65 extend radially inwardly from the bottom of the channel 59 in circumferentially staggered relationship to the passages 64, the passages 65 being aligned with alternate ones of the radial passages 63 axially of the follow-up valve element 32. The slot-like passages 65 are adapted to register selectively with the openings 56 and the adjacent end portions of the grooves 54, in the primary valve element 31, upon relative rotation between the valve elements 31 and 32. The channel 60 of the follow-up valve element 32 is disposed in overlying relationship to the channel 50 of the primary valve element 31, and communication is had between the channels 60 and 50 by a plurality of circumferentially spaced radial passages 66 extending inwardly from the bottom of the channel 60. With this arrangement, when the valve elements [32] 31 and 32 are in their relative neutral positions, with the apertures 61 and 53 in registration, fluid entering through the inlet 3 flows inwardly through the aligned passages 61 and 53 to the recess or passage 33, and from thence outwardly through the passages 52, channel 50, passage. 66 and channel 60 to the outlet 8, and from thence to the reservoir 6 through the conduit 9. It will be noted that the recess or passage 33 is in constant communication with the out let 8 through the channels 50 and 60 and their respective passages 52 and 66.

The internally toothed member 24 comprises the stator of a fluid pressure operated servomotor which also includes an externally toothed member 67 having a less number of teeth 68 than that of the teeth 69 defined by the stator or internally toothed member 24, said member 67 being adapted to rotate on its own axis and partake of orbital movement about the axis of the member 24. The members 24 and 67 are so arranged that the teeth 68 and 69 thereof respectively move into and out of intermeshing engagement and define expanding and contracting nuia chamber 70,1see are. '7', during said "rotary and orbital movement of the member 67'. The construction of the members 24 and 67 is similar to that shown and described in my prior U .8. Letters Patent 2,821,171, and the operation thereof is fully disclosed in said prior Let'- ters Patent. By introducing fluidunder pressure to some of the chambers 70 and permitting fluid to escape from others thereof, the externally toothed member orrotor 67 partakes of an orbital movementabout the axis of the internally toothed member 24. Inasmuch as there are seven stator. teeth 69 and six rotor teeth :68, the externally toothed member or rotor will rotate once on its own axis during six cycles of orbital movement thereof about the axis of: the internally toothed member or stator 24'.

Thecasing structure 2 is provided with a plurality of circumferentially spaced axially extending fluid passages 71 that extend through the bearing plate 23 one each into a difierent one of the chambers 7 between the root portions of adjacent internal teeth 69. At theirinner ends, the fluid passages 71 extend radially'inwardly through the inner cylindrical wall 30 of the tubular casing section 20 radially outwardly of the row of radial passagm 63.

The externally toothed member or rotor 67 is operatively coupled to the follow-up valve element 32 by means or an angularly disposed drive shaft 72 which at its outer end is provided with a 'splined head 73 that is mounted in a central splined opening -7 4 in the rotor 67. With reference to FIGS. 2 and 3, it will 'beseen that the splined head 73 is. rounded to permit angular movements of the shaft 72 relative to the externally toothed rotor member 67. At its opposite end, the drive shaft 72 is bifurcated, as indicated at 75, to receive the central portion of the drive pin 42, whereby rotation of the externally toothed member or rotor 67 is imparted to the followup valve element 32. Axial movement of the drive shaft 72 is limited in one direction by engagement of the splined head 73 with the annular bearing plate 23, and in the other direction by engagement of the outer end of the splined head 73 with a stop plug or'the like 76 contained in the splined opening 74 of the externally toothed member 67 between the head 73 and the endcap-ZS.

For a purpose hereinafter :to be described, I provide .a fluid passage 77 in the tubular casing section 20, said pas sage -77 communicating at its opposite ends with the inlet 3 and the outlet 8, see FIG. 3. At its intermediate portion, the passage 77 is enlarged to [receivea coil compres! sion spring 78 which exerts yielding hiaswagainst a ball check valve 79 toward seating engagement with .an annular valve seat 80 that is screw threaded into :a further enlarged threaded portion-of the passage 77 adjacent the outlet ,8. This arrangement provides for flow ofhfiuid from the outlet 8 to the inlet 3 when fluid pressure is greater in-the outlet .8 :than in the inlet 3.

Asv hereinbefore stated, when the primary valve elemm 31 is in its neutral position relative to the followup valve element 32, fluid under pressure from-the pump 5 flows through the Jcondui-t 4, .inlet 3,, channel 57., radially inwardly through the aligned .apenturesflfand 53,, through the recess '33, channel "50, outwardly through the'ope'n- -ings or passages SZ-and passages 66, and channel i60t0rthe outlet 8,, andrfrom thence to the reservoir othm'ugh the conduit-9.- In this neutral position of the valve element 3.1, it will he noted that both .thegrooves Standtheopenings or passages 55 and 56 aresout of registration with the slot-like passages 64 and 365450 that-thereis no flow of fluid either to or from the cylinder '14, thus providing a fluid'lodk for the piston equipped plunger :1-5. As soon as the control or steering wheel 37 isrotated'inone direotion such as, for instance, a clockwise direction withrespect to FIGS. 4 and 7'14, the apertures 53wi-ll bemoved out of registration with their corresponding apertures 61 and the groove 54 will "be moved. into registration with correspondingpairs of the slot-like passages 65, While the pairs of openings 55 will move into registration the slot-like passages 64. Fluid under pressure will then FIG. 7, to impart orbital movement to the externally toothed member "67, in a counterclockwise direction with respectto FIG. 7. This orbital movement causes c011? traction ofothers of the chambers 70, such as the chambers indicated at E and F in FIG. 7, fluid moving outwardly from thence to others of the passages 71 and radially inwardly through the radial passages 63 in register therewith and with the grooves. 54. With the externally toothed'member 67 positioned as in FIG. 7, the passages 71 leading from the chambers indicated at C, D and G are out of register with their cooperating radial passages 63. As the follow up valve element 32 rotates in common with the externally toothed member '67, the chambers D andCwill become successively contracting chambers operatively connected tothe grooves 54, while the chambersG and F become successively expanding chambers operatively connected to the recesses 51. The grooves 54 being in register with the slot-like passages 65, fluid from the contracting chambers 70 flows to the grooves 54' as immediately above described, outwardly through the passages 65, through the channel 59 in register with the port 11, through the port 11 and conduit 13 to one endof the cylinder 14 to impart movement to the piston equipped plunger rod 1 5 in a direction from the. left to the right with respect to FIG. 1. This movement of the plunger rod- 15 causes fluid to flow from the opposite end of the cylinder 14 through the conduit 12 to the port 10, inwardiy through the s'lotlike passages .64 and openings 55' in'register therewith to the recess or passage 33, and from thence outwardly through the openings 52 and 66 to the outlet 8 to be discharged through the conduit- 9 into the reservoir 6.

It will be appreciated that, during the counterclockwise orbital movement of the externally toothed member 67, the same is rotating in aclockwise directionsimilar to the initial direction of movement of the primary valve element 31 to rotate the follow-up valve element 32 toward a neutral position with respect :to the primary valve element. 31, the amount of common-rotation of the follow-up externally toothed member 67 .andthe valve element 32 being only one-sixth of a completerevolution for each cycle of orbital movement-of the externally toothed memher 67. It will be further appreciated that the follow-up valve element .32 operates in the nature of a-colmnutator to position given ones of the radial passages 63 with given recesses 51, grooves 54 and the passages 71 to direct the fluid. in :a manner :to-eause continued orbital movement of the externally toothed member 6.7 until rotation of e samehas moved .thefollow-up-va-lve element 32 intoits neutral position with respect :to the primary valveelement 31. Obviously, the primary valve element 31 may continue to; :be manually rotated by means of the steering wheel 37 as tiar as desired, the servomotor comprising the toothed mmt bers 24 and 67 continuing to operate until neutrality is obtained between the primary valve element 31 and follow-up valve-element 32.

Rotary. movement imparted, to the primary valve element 351 ina-counterclockwise direction with respect to FIGS. 4. and 7-14causesthelongitudinal grooves 5410 come into-register with the slot-like passages 64 and the openings 56 to be registered with the slot-like passages :65.- .Eluid under pressure isthen delivered the servomotor. to the port 10 .and Irorn thence to said opposite end of. the cylinder 14 through the conduit 12, return fluid being directed from said onexend of the cylinder 14 through the conduit 13 to, the port .11, throughthe aligned openings 65 and5.6 to the recess. or. passage 33., and from thence to the reservoir 6through, theoutlet, 8 and conduit 9,. I'husjit.willbe.seenithatrotation of the control wheel 37 causes the steerable wheels 19 to be swung in one direction, while rotation of the control wheel 37 in the opposite direction causes the steerable wheels 19 to partake of steering movements accordingly.

The yielding bias exerted by the leaf springs 45 against rotary movement or the primary valve element 31 with respect to the follow-up valve element 32, is such that a nominal amount of steering etfort by the operator is required to rotate the Wheel 37 in either direction from the neutral position above described. Due' to theyielding bias of the leaf springs 45, release of the control wheel 37 by the operator will cause the primary valve element 31 to be immediately returned to its neutral position by the springs 45 to shut off flow of fluid to either end of the fluid pressure operated device or cylinder 14.

In view of the fact that all fluid delivered to either end of the cylinder 14 passes through-the servomotor, the servomotor may be used as a pump, operated by manually rotating the control wheel 37 in either direction, to deliver fluid under pressure to a selected end of the cylinder 14, upon failure of the pump 5 to deliver fluid under pressure to the inlet 3. In the event of such pump failure, initial manual rotation of the control wheel 3-7 will cause the primary valve element 31 to be rotated until opposite given ends of the slots 43- engage the drive pin 42 at which point the longitudinal grooves 54 are in registration with the desired slot-like passages 64. or 65 in the follow-up valve element 32. Further rotation of the control wheel 37 will cause the drive shaft 72 to rotate the externally toothed member 67 about its own axis whereby to partake of orbital movements within the internally toothed member 24 and about the axis of said internally toothed member 24. Thus, fluid is directed under pressure tolthe desired end of the cylinder 14 and the fluid returning from the opposite end thereof to the valve structure will set up a pressure in the outlet 8 greater than that within the inlet 3 to cause movement of said ball check valve 79 to an open position against yielding bias of the spring 78, to supply the inlet with fluid to be drawn into the servomotor now acting as a pump. Obviously, the effort required to rotate the control wheel 37 upon such failure of the pump 5, is appreciably greater than that required when the pump 5 is in operation. However, the above described arrangement eliminates the necessity for any mechanical linkage between the control wheel 37 and the steering apparatus and permits my novel controller to be situated at any desired point on a vehicle or any other machine requiring its use.

While I have shown my novel controller as being utilized in the power steering equipment of a vehicle, it will be appreciated that the same may be advantageously used to control fluid pressure operated apparatus in various machines wherein movement of movable devices utilizing fluid pressure operated motors requires control of the extent of movement of the movable devices.

While I have shown and described a commercial embodiment of my novel control apparatus, it will be understood that the same is capable of modification without departure from the spirit and the scope of the invention, as defined in the claims.

What I claim is:

1. A controller for fluid pressure operated devices, said controller comprising; valve structure including a. primary movable valve element and a cooperating movable follow-up valve element; means for connecting said primary valve element to acontrol element for common movement therewith; means coupling said primary valve element to said follow-up valve element for limited movements independently of said follow-up valve element and for common movements therewith; and a fluid servomotor including a movable member coupled to said follow-up valve element for imparting follow-up movements'thereto responsive to movement of said movable member; said valve structure defining, an inlet for connection to a source of fluid under pressure and an outlet for return of fluid to said source, a pair of fluid ports for connection to a fluid pressure operated device, and fluid passages communicating with said servomotor; said'valy'e elements each having valve passages which cooperate to direct flow of fluid from said inlet through said servomotor to one of said ports and to direct flow of fluid from the otherof said ports to said outlet responsive to movement of said primary valve element in one direction away from a neutral position relative to said followup valve element; movement of said primary valve element in the opposite direction from said neutral position causing said valve element passages to be disposed to direct flow of fluid from said inlet through said servomotor to theother of said ports and to direct the flow of fluid from said one of the ports to said outlet; the arrange mentbeing such that the entire stream of fluid flowing from said inlet to the selected one of said ports is conducted through said servomotor; said valve elements in said neutral position relative to each other cutting ofl the flow of fluid to said servomotor.

2. The structure defined in claim 1 in which said valve structure further defines an auxiliary fluid passage between said inlet and said outlet independently of the others of said passages, and in further combination with a valve normally closing said auxiliary passage when the inlet pressure is greater than the outlet pressure and opening said auxiliary passage during reversal of said pressure to permit flow of fluid from said outlet to said inlet.

-3. A controller for fluid pressure operated devices, said controller comprising; body structure defining a cylindrical chamber; a cylindrical primary valve element journal-led in said body structure and extending axially within said chamber; a tubular follow-up v-alve element concentrically journalled on said primary valve element within said chamber; means for imparting rotation to said primary valve element from a neutral position; means coupling said valve elements together, for independent rotation relative to each other between predetermined limits and for common rotation; said body structure defining, an inlet for connection to a source of fluid under pressure, an outlet for return of fluid to said source, and a pair of fluid ports for connection to a fluid pressure operated device; said body structure including a stationary annular internally toothed member concentric with said chamber; an externally toothed member having a less number of teeth than said internally toothed member and mounted in meshing engagement therewith for orbital and rotary movements within said internally toothed member; said toothed members cooperating to provide a servomotor; means coupling said externally toothed member to said follow-up valve element for common rotation therewith; said body structure defining fluid passages communicating with said servomotor; said valve elements each having valve passages which cooperate to direct flow of fluid from said inlet through said servomotor to one of said ports and to direct flow of fluid from the other of said ports to said outlet responsive to rotation of said primary valve element in one direction away from said neutral position relative to said followup valve-element; rotation of said primary valve element in the opposite direction from said neutral position causing said valve element passages to be disposed to direct flow of fluid from said inlet through said servomotor to the other of said ports and to direct the flow of fluid from said one of the ports to said outlet; the arrangement being such that the entire stream of fluid flowing from said inlet to the selected one of said ports is conducted through said servomotor; said valve elements in said neutral position relative to each other cutting off the flow of fluid to said servomotor.

4. The structure defined in claim 3 in which said body structure further defines an auxiliary fluid passage between said inlet and outlet independently of the others of said passages, and in further combination with a valve normally closing said auxiliary passage when the inlet pressure is greater than the outlet pressure and opening independently of said common .movements therewith and including a resilient during reversal of said pressurerto said inlet through said auxiliary passage permit flow of fluid firorn said outlet to said auxiliary passage.

5. The structure defined in claim 3 in which said primary valve element defines an axial recess extending firom one end of said primary valve element for the greater part of its length, said means coupling the valve elements together comprising a transverse drive pin connected at its opposite end portions to diametrically opposed portions of said follow-up valve element, said primary valve element having-diametrically opposed circumferentially extending slots for free reception of said drive pin, the opposite ends of said slots engaging said drive pin to limit said independent movement of the primary valve element.

6. The structure defined in claim 5 in which said means coupling the externally toothed member to said followup valve element comprises a drive shaft connected at one end to said externally toothed member for common rotation therewith. and for angular movements with respect thereto, the other end of said drive shaft being bifurcated for reception of the intermediate portion of said drive pin within said recess in the primary valve element.

7. The structure defined in claim 6 in further combination with spring means yieldingly urging one of said valve elements in a direction of rotation relative to the other of said valve elements to center said drive pin between said opposite ends of said slots in the primary valve element and dispose said primary valve element in said neutral position relative to the follow-up valve element.

8. A controller for fluid pressure operated devices, said controller comprising; valve structure including a primary movable valve element and a cooperating movable followup valve element; means for connecting said primary valve element to a control element for common movements therewith; and a fluid servomotor including a rotary member coupled to said follow-up element for imparting follow-up movements thereto responsive to rotation of said rotary member; said valve structure defining, an inlet for connection to a source of fluid under pressure and an outlet for return of fluid to said source, a pair of fluid ports for connection to a fluid pressure operated device, and fluid passages communicating with said servomotor; said valve elements each having valve passages which cooperate to direct flow of fluid from said inlet through said servomotor to one of said ports and to direct flow of fluid from the other of said ports to said voutlet responsive .to movement of said primary valve .element in one direction away from a neutral position relative to said follow-up valve element; movement of said primary valve element in the opposite direction from said neutral position causing said valve element passages to be disposed to direct flow of fluid from said inlet throughsaid servomotor to the other of said ports and to direct flow of fluid from said one of the ports to said outlet; the arrangement being such that the entire stream of fluid flowing from said inlet to the selected one of said ports is conducted through said servomotor; said valve elements in said neutral position relative to each other cutting off the flow of: fluid to said-servomotor.

9. A controller for fluid pressure operated devices, said controller comprising; valve structure including a primary movable valve element and a cooperating movable follow-up valve element; means for connecting said primary valve element to a control element for common movement therewith "11 either direction from .a neutral position; means coupling said primary valve element to said follow-up valve element for limited movements follow-up valve element and for member yieldingly urging said valve elements toward relative neutral positions wherein said primary valve element is disposed centrally between the limits of said independent movement thereof relative to said follow-up valve element; and a fluid servomotor including amovable member coupled to said follow-up element for imparting follow-up movements thereto responsive to movement of said movable member; said valve structure defining-an inlet for connection to a source of fluid under pressure and an outlet for return of fluid to said source, .a pair of fluid ports for connection to a fluid pressure operated device, and fluid passages communicating with said servo motor; said valve elements each having valve passages which cooperate to direct flow of fluid from said inlet through said servomotor to one of said ports and to direct flow of fluid from the other of said ports to said outlet responsive to movement of said primary valve element in one direction away from said neutral position relative to said follow-up valve element; movement of said primary valve element in the opposite direction from said neutral position causing said valve element passages to be disposed to direct flow of fluid from said inlet through said servomotor to the other of said ports and to direct the flow of fluid from said one of the ports to said outlet; the arrangement being such that the entire stream of fluid flowing from said inlet to the selected one of said ports is conducted through said servomotor said valve elements in said neutral position relative to each other cutting ofi the flow of fluid to said servomotor.

10. In combination with a fluid pressure operated device and a source of fluid under pressure therefor, a controller comprising; valve structure including a primary movable valve element and a cooperating movable follow-up valve element; means for connecting said primary valve element to a control element .for common movement therewith; means coupling said primary valve element to said follow-up valve element for limited movements independently of said follow-up valve element and for common movements therewith; and a fluid servomotor including, a movable member coupled to said follow-up valve element for imparting follow-up movements thereto responsive to movement of said movable member; said valve structure defining, an inlet connected to said source of fluid and an outlet connected to said source for return of fluid thereto, a pair of ports connected to said fluid pressure operated device, and fluid passages communicating with said servomotor; said valve elements each having valve passages which cooperate to direct flow of fluid from said inlet through said servomotor to one of .said ports and to direct flow of fluid from the other of movement of said primary valve element in the opposite direction from said neutral position causing said valveelement passages to be disposed to direct flow of fluid from said inlet through said servomotor to the other of said ports and to direct the flow of fluid from said one of the ports to said outlet; the arrangement being such that the. entire stream of fluid flowing from said inlet to the selected one of said ports is conducted through said servomotor; said valve elements in said neutral position relative to each other cutting off the flow of fluid to said servomotor.

11. A controller for fluid pressure operated device s, said controller comprising; body structure .defining a cylindrical chamber; a cylindrical primary valve element journalled in said body structure and extending axially within said chamber; a tubular follow-up valve element concentrically journalled on said primary valve element within said chamber; means for imparting rotation to said primary valve element from a neutral position; means coupling said valveelements together for independent rotation relative to each other between pre-detersure operated device; and a servomotor comprising an internally toothed member and an externally toothed member; said externally toothed member having a less number of teeth than said internally toothed member and in meshing engagement therewith; one of said members being stationary and the other thereof being movable in an orbit about the axis of the stationary member and rotatable on its own axis responsive to said orbital movement; said follow-up valve element being coupled to said movable member for common rotation therewith; said body structure defining fluid passages communicating with said servomotor; said valve elements each having valve passages which cooperate to direct flow of fluid from said inlet through said servomotor to one of said ports and to direct flow of fluid from the other of said ports to said outlet responsive to rotation of said primary valve element in one direction away from said neutral position relative to said follow-up valve element; rotation of said primary valve element in the opposite direction from said neutral position causing said valve element passages to be disposed to direct flow of fluid from said inlet through said servomotor to the other of said ports and to direct the flow of fluid from said one of the ports to said outlet; the arrangement being such that the entire stream of fluid flowing from said inlet to the selected one of said ports is conducted through said servomotor; said valve elements in said'neutral position relative to each other cutting off the flow of fluid to said servomotor.

12. A controller for fluid pressure operated devices, said controller comprising; body structure defining a cylindrical chamber; a cylindrical primary valve element journalled in said body structure and extending axially within said chamber; a tubular follow-up valve element concentrically journalled on said primary valve element within said chamber; means for imparting rotation to said primary valve element from a neutral position relative to said follow-up v-alve element; means coupling said valve elements together for independent rotation relative to each other between predetermined limits and for common rotation and including a resilient member yieldingly urging said valve elements toward relative neutral positions wherein said primary valve element is disposed centrally between the limits of said independent rotation thereof; said body structure defining, an inlet for connection to a source of fluid under pressure, an outlet for return of fluid to said source and a pair of fluid ports for connection to a fluid pressure operated device; and a servomotor comprising an internally toothed member and an externally toothed member; said externally toothed member having a less number of teeth than said internally toothed member and in meshing engagement therewith; one of said members being stationary and the other thereof being movable in an orbit about the axis of the stationary member and rotatable on its own axis responsive to said orbital movement; said follow-up valve element being coupled to said movable member for common rotation therewith; said body structure defining fluid passages communicating with said servomotor; said valve elements each having valve passages which cooperate to direct flow of fluid from said inlet through said servomotor to one of said ports and to direct flow of fluid from the other of said ports to said outlet responsive to rotation of said primary valve element in one direction away from said neutral position relative to said follow-up valve element; rotation of said primary valve element in the opposite direction from said neutral position causing said valve element passages to be disposed to direct flow of fluid from said inlet through said servomotor to the other of said ports and to direct flow of fluid from said one of the ports to said outlet; the arrangement being such that the entire stream of fluid flowing from said inlet to the selected one of said ports is conducted through 'said servomotor; said valve elements in said neutral position relative to each other cutting ofi the flow of fluid to said servomotor.

13. A controller for fluid pressure p rated devices, said controller comprising; valve structure including a primary movable valve element and a cooperating mov able follow-up valve element; means for connecting said primary valve element to a control element for common movements therewith; and a fluid servomotor including a rotary member coupl d to said follow-up element for imparting follow-up movements thereto responsive to rotation of said rotary member; said valve structure defining, an inlet for connecti n to a source of flu'id under pressure and an outlet for return of fluid to said source, a pair of fluid ports for connection to a fluid pressure operated device, and fluid passages communicating with said servomot r; said valve elements each having valve passages which cooperate to direct flow of fluid from said inlet through said servomotor to one of said ports and to direct flow of fluid from the other of said ports to said outlet responsive to movement of said primary valve element in one direction away from a neutral position relative to said follow-up valve element; movement of said primary valve element in the opposite direction from said neutral position causing said valve element passages to be disposed to direct flow of fluid from said inlet through said servomotor to the other of said ports and to direct flow of fluid from said one of the ports to said outlet; the arrangement being such that the entire stream of fluid fl wing from said inlet to the selected one of said ports is conducted through said servomotor.

14. A controller for fluid pressure operated devices, said controller comprising; valve structure including a primary movable valve element and a cooperating movable follow-up valve element; means for connecting said primary valve element to a control element for common movement therewith; means coupling said primary valve element to said follow-up valve element for limited movements independently of said follow-up valve element and for common movements therewith; and a fluid servomotor including a movable member coupled to said follow-up valve element for imparting follow-up movements thereto responsive to movement of said movable member; said valve structure defining, an inlet for connection to a source of fluid under pressure and an outlet for return of fluid to said source, a pair of fluid ports for connection to a fluid pressure operated device, and fluid passages communicating with said servomotor; said valve elements each having valve passages which cooperate to direct flow of fluid from said inlet through said servomotor to ne of said ports and to direct flow of fluid from the other of said ports to said outlet responsive to movement of said primary valve element in one direction away from a neutral position relative to said follow-up valve element; movement of said primary valve element in the opposite direction from said neutral position causing said valve element passages to be disposed to direct flow of fluid from said inlet through said servomotor to the other of said ports and to direct the flow of fluid from said one of the ports to said outlet; the arrangement being such that the entire stream of fluid flowing from said inlet to the selected one of said ports is conducted through said servomotor.

15. A controller for fluid pressure operated devices, said controller comprising; valve structure including a primary movable valve element and a cooperating movable follow-up valve element; means for connecting said primary valve element to a control element for common movement therewith in either direction from a neutral position; means coupling said primary valve element to said follow-up valve element for limited movements independently of said follow-up valve element and for common movements therewith and including a resilient member yieldingly urging said valve elements toward relative neutral positions wherein said primary valve element is disposed centrally between the limits of said independent movement thereof relative to said follow-up valve element; and a fluid servomotor including it movable mem,

ber coupled to said follow-up element for imparting follow-up movements thereto responsive to movement of said movable member; said valve structure defining, an inlet for connection to a source of fluid under pressure and an outlet for return of fluid to said source, a pair of fluid ports for connection to afluid pressure operated device, and fluid passages c mmunicating with said servomotor; said valve elements each having valve passages which cooperate to direct flow of fluid from said inlet through said servomotor to one of said ports and to direct fluid from the other of said ports to said outlet responsive to movement of said primary valve element in one direction away from said neutral position relative to said follow-up valve element; movement of said primary valve element in the opposite direction from said neutral position causing said valve element passages to be disposed to direct flow of fluid from said inlet through said servomotor to the other of said ports and to direct the flow-of fluid from said one of the ports to said outlet; thearrangement being such that the entire stream of fluid flowing from said inlet to the selected One of said ports is conducted through said servomotor.

16. A controller for fluid pressure operated devices, said controller comprising; body structure defining a cylindrical chamber; a cylindrical primary valve element journalled in said body structure and extending axially within said chamber; a tubular follow-up valve element concentrically journalled on said primary valve element within said chamber; means for imparting rotation to said primary valve element from a neutral position; means coupling said valve elements together for independent rotation relative to each other between pred termined limits and for common rotation; said body structure defining, an inlet for connection to a source of fluid under pressure, an-outlet for return of fluid to said source, and a pair of fluid ports for connection to a fluid pressure operated device; and a servomotor comprising an internally toothed member and an externally toothed member; said externally toothed member having a less number of teeth than said internally toothed member and in meshing engagement therewith; one of said members being stationary and the other thereof being movable with its axis moving in an orbit about the axis of the stationary member, the movable member being rotatable on its own axis responsive to said orbital movement; said follow-up valve element being coupled to said movable member for common rotation therewith; said body structure defining fluid passages communicating with said servomotor; said valve elements each having valve passages which cooperate to direct flow of fluid from said inlet through said servomotor to one of said ports and to direct flow of fluid from the other of said ports to said outlet responsive to rotation of said primary valve element in one direction away from said neutral position relative to said follow-up valve element; rotation of said primary valve element in the opposite direction from said neutral position causing said valve element passages to be disposed to direct flow of fluid from said inlet through said servomotor to the other of said ports and to direct the flow of fluid from said one of the ports to said outlet; the arrangement being such that the entire stream of fluid flowing from said inlet to the selected one of said ports is conducted through said servomotor.

References Cited in the file of this patent or the origmal patent UNITED STATES PATENTS Charlson Jan. 28, 

